An object detector may detect an object from radiation in a particular wavelength range. For example, the object detector may produce a transmission signal in a radar wavelength range. The transmission signal covers, as it were, a detection area around the object detector. An object that is present in this detection area will cause a reflection of the transmission signal in the radar wavelength range. The object detection module may then detect the object from this reflection, which emanates from the object. As another example, the object detector may detect a relatively warm object, such as, for example, a person, from a radiation that emanates from the object in an infrared wavelength range.
A lighting system may comprise respective lighting units that are provided with respective object detectors. In case an object detector of a lighting unit detects an object, the object detector may cause the lighting unit to be in an active mode. The object detector may also cause a neighboring lighting unit to be in an active mode if, for example, the object is moving towards this neighboring lighting unit. Conversely, in case an object detector of a particular lighting unit does not detect any object, and neighboring object detectors of neighboring lighting units neither detect any object, the particular lighting unit may be in an idle mode. This saves power and reduces so-called light pollution.
In a lighting system as described above, the respective lighting units may further be provided with respective communication modules. Accordingly, a lighting unit may transmit a message to another lighting unit or to a system controller. For example, the message may comprise identification data, data concerning detection of an object, or data concerning a failure within the lighting unit. The respective communication modules further allow the system controller to send data, such as a command, to a particular lighting unit, or a particular group of lighting units.
UK patent application published under number GB 2 444 734 describes a street lighting system that provides illumination for objects passing along a roadway. The presence of objects is detected by one or more sensors, which may be in the form of motion detection radars.